Preparation of light-colored fresh fruit for market



4 Patented Sept. 14, 1943 eammmma moirr-o :7 FRUIT FOR MARKET p I M Y Charles nloothmn','romonafcalirgassi no fiby;

01.61am) FRESH mesne assignments to Brogdx-Company, a-

i corporation. or California No Drawing. Application July 24,1941,

' Serial No. 402,9.or j w 6 Claims. f(o1.99 1 03) V t I packers were obliged tov modify their'waxing invention relates to preparation of light colored fresh fruitionmarket; andit relates more .particularly to improvements inthe pracmethods somewhat in order tocomply withthetice of providing lemons, 'which. have" a .rind of predominantly yellow or yellowishcolor and are commercially classified, when ready for shipment to market, into various quality .grades'in which'the particular shade ofyellow isavitally controlling factor, .with a substantially transparent Waxy. coating not, onlysuitable'tojpen' formthe indispensable function of greatly r'etardirig. withering or shriveling but also of such character as to present a glossy. or shiny surface produced in various known ways. The pur pose of the present improvements is to prevent. lemons or other light-co1oredfresh fruits the commercial grading of which depends to atom.

siderable extent .upon. their. relative .lightnessjon delicacy of .color' shade in."comparisonwithcus-i tomary trade standards, from ,being .wronglyi graded after they haveheenprovided withsuch a, glossy or lustrousfcoatin'g of waxy material."

.,Alth0-ugh the. invention can. be usefully employed ,in handling light-colored. fruit other than lemons, it is in the lemon'packing ind sei try that the invention is of. greatest present 'utility and importance... In' explaining'the principles of' the. invention hereinafter, therefore,. reference will be mademore, particularly to the. commercial handling of lemonsbyway of il1us-.

trative example, but withoutimplying that prac-.

tice of the invention is necessarily limited to this particular field.

Althwgh high gloss or p h'has 'always .te'ei regarded by the trade as afdefinitely' desirable characteristic of wax-coated oranges, an ,ex

actly opposite preference in the case of waxcoated lemons'had always been. manifested by the trade up .to' onlysaxfewyears ago, and the compositions. and methods employed .for' waxing lemons up tolthat' timehad' always been such aswould ensure the lemons having a relatively dull or luster'less surface .when shipped to market. A few years ago,-howevjer; there"developed a trade preference for wax-coated lem-" ons having a. high glossor polish, whereupon the lemon packers and pShippers were obliged to nieet this changed demand and toalter their waxing methods accordingly. .Up. to that time,

the practice of waxing, which had become Well established in this country and virtually mandatory in packing all fresh citrus fruits .for shipment to market, had proved thoroughly satisfac tory in the lemon packing industry as well as m the crangepacking industry. But after lemon, 5o.

aforesaid changed trade demandfor waxcoated lemons having a glossy instead.of-a relatively waxed; lemons must bev due to some. adverse. ac

tion orthe coatin' material onthie fruit rind causing the c0103 d'darkerr f Although this was not actuallyso, and although decreaseiijn normal percentage of .firstffgrade'fruit was inreality'due. to a false classification or grading not thenape preciated, lemon growers and shippers suffered. substantial'los'ses from. this difficulty for 1a long time, duringwhich 'therefwere repeated unsuccessful effortsto.remedytheidiificulty;

' According to the present invention, the afore said drake-classification of' high grade .lemonsj as lower. gradejJemons, consequent upon the,

stated change on lemon-waxing procedure, .is efi'ectively preventedflin a simple, practical and economical manner, whereby lemon growers and T shippers are savedsubstantiallosses, long re garded as inseparable fromthe, practice of waX-. ing lemons where arelatively, high gloss orp l ad-t b produced- It well nown fact that the trade has a pronounced preference for; lemons that are. r 1

lemonjyello'w in'color. This designation je mbraces ia,substantial range of specific color shades or'tints from paleyellow to deeper shades that arestill substantially free of a pronounced I reddish or .copperyj, tint.

ingly with the wellj known great desirability in the case of oranges, of relatively high .coloration, as evidenced by the various expedien'ts, such as dyeing, that are resorted to in order to obtain the ideal deep orange shades.

cluded in the first; grade, provided it does not show a distinct coppery tint, or fbronzirigi as it is scmetimes'c'alled; A fairly pale shade. of yel- V low isfcustomarily regarded. as characteristic. of

lemons injp'r'ime condition inrespectto proper degree of maturity,'juice content, 'ireshness and. otherI.qualitiesv important .ior edibility. Pro-f nouncedjhigh coloration .(a relatively deeper in- This contrasts strik The officialj egulations established for the grading of lemons permit a' certainipercentage of bright yellow .orfully colored fruit to be in-,.

tense and darker shade of yellow), if it includes reddish or coppery tinting, is regarded as indicating overma'turity and lack of freshness, as well as degrees of maturity in storage, sometimes for months, in order to develop proper color, juice availability and other desirable characteristics before packing them out forshipment to mark et, it is to be expected that a rather substantial percentage (in some cases well over 50 per cent) of lemons produced will fail {to meet the true lemon yellow standard set for commercial first grade lemons. No matter how carefully the temperature, humidity and other conditions'of storage are controlled, more or less of the lemons unlemons is lowered to include more than the permissible small proportion of relatively highly colored fruit in the first grade, a shipment of such first grade lemons is likely to be seriously penalized upon arrival and inspection at the marketing destination. This is because the shipment as a whole is likely to be ofiicially reported as red, bronze, aged, or otherwise designated as inferior in marketing quality, and hence to sell only at a substantial price concession; this, in spite of theme thatnearly all or much the greater part of the'fruit in the shipment is actually perfectly sound and first grade. The risk of incurring such a penalty therefore impels most lemon packers r and shippers to err on the side of safety by putting all doubtful fruit into the second grade.

dergo over-coloring or bronzing, the extent of this depending upon many factors including local soil, climatic and other cultural conditions. for any given producing locality, the percentage of lemons that should normally bepacked out is rather definitely known. I

Since first grade fruit naturally brings the highest price, lemon growers and Shippers are vitally interested in seeing to it that as large a proportion of their lemon output as possible gets into the first or highest quality grade. Anythingv which decreases the proportion of their fruit nor mally going into the first gradev and causes .a larger than normal proportion of it to be placed But, I

in a lower grade, is therefore highly objectionable and to be avoided so far as possible because of the resultant serious reduction in profits.

The separation of lemons into the commercially:

recognized shipping grades occurs'as the last step of their handling through thepacking house at the locality of production, just before they are actually placed in the shippingcrates or boxes in which they are transported to'market; In this final gradingor sorting, the lemons are separated according to surface appearance, taking into ac count the, different shades and uniformity of yellow coloration, as well as rind texture and the presence or absence of surface injuries, into established commercial marketing grades. Usual 1y these grades arefirst, second and'standard.

The grading is done by expert graders who, through long experience and constant practice, are able to distinguish accurately at a glance, and pick out, these several recognized grades as the lemons are carried past them ma continuous stream resting on the gradingbelt'to which the lemonsare delivered from preceding packing 'op-' erations. Only fruit of the best quality is selected for the first grade; that is, fruit of substantially uniform coloration within the range of shades. included in true lemon yellow, and having a. smooth fine-textured rind practically free from T surface blemish. Second grade fruit is so classi-.

fied either because it is less perfect in respect to rind texture and freedom from blemish, or.

posed of; Where the'standard of grading of the have been packers of oranges.

:For nearly twenty years, it has been regular established practice, in preparing lemons and otherflcitrus fruits for shipment to market from the locality of production, to provide them with a transparent protective coating of wax or waxy composition, so extremely thin as to be almost imperceptible but, when properly applied, effective'to reduce considerably the loss of moisture through the skin or rind normally suffered by unprotected lemons while they are being prepared for market and distributed to the trade and to ultimateconsumers. In some cases the coating is applied to the lemons only just before final grading and shipment; in others, it-is applied also prior to storing or curing them. This is especially necessary where, as is usual whether or not they are to be stored, the'lemons brought in from the groves are subjected to a thorough cleansing with warm water usually containing soda ash and frequently other additions such as soap, solvents derived from petroleum, .or other cleansing aids, in order to remove dust,.oily soot, insect deposits and foreign matter of all kinds. Such cleansing treatment also commonly removes some of the natural oily and waxy constituents of the rind or peel, thus tending to, deprive the fruit to some extent of'its natural protection against withering or shrinkage and to accelerate the rate at which this can normally be expected to occur in unwashed fruit. By properly applying a Very thin coating of suitable waxy material in ways now well known to those skilled in'the art, it has long been feasible not only to. offsetthis increase in rate of shrinkage, but also to go much farther and to reduce the rate of shrinkage to one-half or less of that which is normal to fruit even in its natural or untreated conditiorn Because the fruit'is thereby effectively maintained firm, plump and in generally fine fresh condition throughout the period of shipment, distribution and delivery through the ordinary trade channels and into the'hands of the ultimate consumer, the practice of providing it with a waxy protective coating has proved highly beneficial to growers and shippers and, in .the citrus fruit industry especially, hasbeen so universally adopted as long since to have become virtually mandatory practice in packing lemons as well as oranges.

Fora, long time after it became regular commercial practice to protectively wax-coat lemons, lemon packers were quite as thoroughly pleased and satisfied with the results of the ,practice as The compositions and methods most commonly employed for waxing lemons were certain of those disclosed, for example, in the patents to Brogden 1,585,371 and Trowbridge and Cothran 2,196,164; the waxy material employed being paraflin, with which was usually admixed an oil of the Nujol type.-

luster orpolish, and it isstill notthe practice todoso.'- I 3 i After investigating at great length, without useful result, a number of possible causes ofithe trouble, such as the possibility that the waxy materialsemployed, including those added to enhance the luster or polish, might act 'uponfthe'.

rind to produce a ;pigmentaryfchange resulting in deeper coloration, .or that the more. extensive brushingor theuse of heatmight be a contributing cause, this applicant finally"discovered that the explanation lay'not in any deep-1 ening of the actual rind coloration, but in an optical effect resulting from the high polish orgloss on the outer or exposed surface of the.

transparent waxy layer encasing l the lemons,

whereby lemonswhose rind is actually of a yel-J low shade included within the color range permissi'ble for the first gradelemons, but in the:

deeper-tinted portion of said range, are caused to appear more highly colored than they actually are and than is acceptable for firstgrade fruit. As a consequence, most of such lemons,which may be termed border-line first grade fruit and-which are actually of first grade quality in every re could be remedied by. imparting in any suitwere;

in those, wave lengths; corresponding to blue and green; as compared to thetotal light reflectance from the surface of the same lemon either unwaxed or provided with a waxy coating that is much less lustrous. Whether'this is due to light dispersion or absorption, or both, 'and whether or not the curvature of the surfaces concerned also enters into the matter, there is in any event an apparent deepening or bronzing of the natural yellow of the lemon by reason of the relatively greater proportion of the, longer orange able manner to the glossy transparent waxy.

coating of the lemons a tint within the bluegreen range sufiicient to correct or compensate for the apparent lowering of the color grade, thereby restoringthe appearanceof the fruit,

so far as concerns degree of rind-coloration, to

what it was before the lustrous coating was applied. By carefully adjusting and controlling;

the degree .to which the coatingis tinted, the desired effect can be prqoduced without the tinting itself being noticeable upon inspection of the fruit. The effect is to neutralizev or cor-.- rect the cause, whatever it may be, formerly re-- sponsible for the failure of the actual color of andred wavelengths in the total light reflected from the surface 0f the lemon when its waxcoating is highly burnished or glossy. Consequently, if. the/actual. color of the lemon has developed to a point where its shade of yellow approaches but does not exceed the minimum depthor intensity permissible for including it in first grade fruit, and if that lemon be then providedv with an uncorrected. waxy coating having a high luster or polish, the lemon will appear to the grader toQbe. higher colored and of a more intense or deeper yellow shade than is permissiblein first grade lemons. The grader will accordingly put it into the second grade in spite of the fact-that it is "actually a first grade lemon. But-coloring the waxy coating by means of a dye within the blue-green range,

in accordance with the principles of the inven-- tion, makesiup or compensates for the aforesaid deficiency of the total light reflectance in respect to wave lengths between yellow and vio- 'Inarketingdestination to which it is shipped,

such a lemon then appears to'be, asit actually is, a first grade lemon.

the lemon tobe transmitted through and from the glossy waxy coating to the eye ofan observer. Employment of the invention inpractice has now demonstrated that this simple expedient provides a completely satisfactory solution of the problem which for some years had proved so troublesome and expensive to packers.

In practice, a simple and efiective way to; ac-

complish the corrective tinting of 'the lustrous waxy coating is to incorporate with' the waxy material thereof (a wax or wax-oil composition) prior to applying the same-to the fruit, the neoessaryvery small proportion ofsomecoloring matter, such as an oil-soluble dye, within the bluegreen range that is compatible therewith, i. 'e."

miscible with or soluble in said waxy material to such an extent as substantially not to diminishthe transparency ofthe applied-waxy coat-,

seems reasonableto suppose that, due to giv ing an uncorrected waxy coating on the lemon a high luster or polish, the totallight reflectance from the surface of the lemon itself,

through and from the transparent waxy layer,

is rendered more or less deficient in those wave lengths between yellow and violet, particularly.

Typica'l oil-soluble dyes suitable for use in practicing theinvention are :National D and C Green #6 (otherwise known as Quinazarine Green SS), --Oil Green Q261, Oil Blue 1800, Oil Blue B Base, Oil Blue Green and Oil Green Q Base. All these dyes are obtainable from National. Aniline and Chemical Company under. the .nameseindicated. Use of the first mentioned dye, National D and C Green #6 (QuinazarineGreen SS), inpracticing the invention is consistent with thepresent ofiicial requirements under thev Pure Food. and Drug Act.

The proportion of dye necessary to employ in the waxy coating in order to effect the desired correction for apparently'deepened rind coloration-due to the gloss or shine isrelatively minute, being in any, event only, a small fraction of one per centby weight'of the waxy material (wax. or wax plus non-volatile oil) used for the protective coating. Less than 1 part of dye'to 5000 parts of waxy material is ordinarily not likely to produce, useful results, while it is practically never necessary to use a larger pro" portion of dye than 1 part to 1500 parts of waxy material. A proportion range of from 1:3500 to 112500 represents typical good practice. This is insufficient to give more than a mere trace of dye in the coatingon a lemon, and there is no dyeing of the lemon rindor peel itself; Thus, assuming that the proportion of dye to Waxy material is 1:3000; the protective coating on a single lemon carries on the order of about 0.06 milligram of 'dye, in a; typicalinstance. This gives the transparent glossy waxy coating a greenish or bluish green cast which may be so slight as to be quite unnoticeable but which isv effective, probably at least in part as a light screen or filter, to accomplish the correction classification or grading of lemons through the- 1,940,530, the required minute proportion of suitable green or blue-green dye may simply be mixed with the molten waxy material in the proportion'of 1:3000,forexample, and thus dissolved therein, thecolored molten waxy material then being -atomized in contact with the lemons as they pass over revolving polisher brushes ina heated chamber, in the manner de-- scribed in said patents. The'waxy material may consist, for example, of a mixture of 90 parts of paraflin wax and parts of a non-volatile mineral oil such as a good grade of white or medicv inal oil. Whereithe brushing of the lemons is sufficiently vigorous and prolonged, a good polish or gloss is obtainable even where as much as parts of the white mineral oil are mixed with '75 parts of parafiin. Using 1. part of National- Anilin D and. C Green #6to from 2000 to 2500 parts of suchia wax-oil mixture gives good results. I Als'omewhat; higher'polish is obtainable where the mineral oil is entirely omitted, especially where a portion of the parafiinis replaced by 'earnauba wax. Thus, where themolten wax material atomized or fogged uponthe lemons as they pass over the polisher brushes consists of 99 parts parafiinand 1 .part carnauba wax,

with no accompanying non-volatile oil, aneven higher polish is obtainable, which may be still further enhanced by increasing theproportion of carnauba to as much as 5 percent or more if desired. Where carnauba is employed as one of y the waxy constituents,the slightly amber tint which it gives the coating mixture renders it advisable to use aslightly higher proportion of the green or blue-green dye than where parafiin is the only waxy component.

Where the waxy material isfappliedto the lemons in solution in a volatile non-aqueous solvent as is sometimes done'in practice, the

" dye may be dissolved directly inthe solvent along with the waxy material; the colored wax solu-. tion then being sprayed or atomized on the The, foregoing examples are, merely typical of ways in which the principles of the invention can be applied inpractice in preventing false color unavoidable apparent deepening of theircolora tion" formerly resulting when providing them with protective waxy coatings" having a high luster or polish. The same principles can be extended to the provisions of lustrous waxy coatings on other fresh fruits, such as grapefruit, where,- in the commercial grading or classification of the fruit, a premium, is or maybe placed upon the lighter shades of coloration.

What is claimed is:

1.In a process of providing fruitthat has a yellow rind and is customarilygraded at least partly on'the basis of the lightness or delicacy of its color shading, with a substantiallytrans parent glossy protective coating of waxy material, theimprovement which comprises imparting to the material of said coating a tint within theblue-green range in order to correctthe apparent lowering of color grade due to the presence of said coating on the fruit.

2. In a process of providing lemons with a substantially transparent glossy protective coating ofwaxy material, the improvement which comprises coloring the material of said coating by means of coloring matter compatible there-: with and within the blue-green range in order to correct the apparent lowering of color grade due to' the presence of said coating on thefruit.

3. In a process of providing lemons witha substantially transparent glossy protective coating of waxy material, the improvement which comprises incorporating with said Waxy material before its application to the lemons a sumcient smallproportion of an oil-soluble dye within the blue-green range to correctthe apparentlowerving'of color grade due to the presence of said coating on the fruit.

4. In. the art of preparing for market 'fresh fruit that has a yellow rind and is customarily graded at least partly on the basis of the light ness or delicacy of its color shading, the method fruit, or the fruit being dipped in the solution,

in the manner well understood in the art; the

fruit being subsequentlybrushed or rubbed if necessary, afterevaporation of the volatile solvent,-to produce a high .luster or polish.

Where the lustrous waxy coating on. the

lemons is obtained by application of an aqueous emulsion of the way material, whether this be of the dry-bright type or of a type requiring subsequent brushing to obtain a high polish, the required minute proportion "of green or'bluegreen dye may be'incorporated with the waxy material prior to emulsificatiom'and the emul- I sion applied in the usual way, with production of a green-tinted lustrous waxy coating, on Y the lemons having substantially the same advantages as the other waxy' coatings already described.

which comprises providing such'iruit with a glossytransparent protective coating ofvwaxy material having a tint within the blue-green range, and then color-grading the fruit.

5. 'In the art of preparing lemons for market, a

the method which comprises providing lemons witha glossy transparent protective coating of waxy material colored by means of coloring matter' compatible therewith and within the blue-- {green range, and thencolor-grading the wax- -.coated lemons.

' 6.-In the art of preparing lemons for market,

1 the method which comprises providing lemons with a glossy transparent protective coating of waxy material having incorporatedtherewith a minuteproportion of an oil-soluble dye within the blue-green range, and then color-grading the wax-coated lemons.

CHARLES D. COTHRAN'. 

